Thanks. You just killed the thread in the first post with this unarguably truth.

Actually no you are completely wrong.

That is his car.
He is has a multimillion dollar sponsorship with Kia.
As such they give him free Kia vehicles to drive around.
Product placement is an important part of product advertisement (eg Evian water bottles at ALL ATP/WTA wimbledon 2012 interviews)
Social media sites like Facebook/Twitter are an advertising medium for product placement.
Rafa is doing his part by having product placement in his photos. Here he is caringly washing his Kia, showing appreciation and care for his car.
Desired effect - If a huge star like Rafa likes his Kia it must be a good car, boy o boy i want my next car to maybe be Kia cuz its a good car like Rafa knows it is.
Rafa has been hawking* sponsors services and good in his recovery period (eg pokerstars)